Tundish nozzle construction



United States Patent 3,451,594 TUNDISH NOZZLE CONSTRUCTION Sigmund W.Stewart, 385 Dorothy Lane, Wyckolf, NJ. 07481 Filed May 17, 1966, Ser.No. 550,775 Int. Cl. B67d 1/08, /72, 35/38 U.S. Cl. 222-152 2 ClaimsABSTRACT OF THE DISCLOSURE The commercial use of processes for thecontinuous casting of steel seems destined to take an increasinglyimportant position in contemporary steelmaking. Its many advantages interms of cost, labor, and simplicity of practice make it very attractiveto a highly automated industry.

Continuous casting is generally defined as the making of a casting manytimes the length of the mold in which it is produced. Molten steel ispoured into an open bottom mold of the desired product shape. The steelis cooled in the mold just enough to harden the exterior surface of thecasting, which forms a shell or container to hold the balance of theliquid metal. The partially solidified easting is then continuouslywithdrawn from the bottom of the mold, where it is further cooled bywater sprays until all the metal is solidified.

Preparing liquid metal for pouring and handling hot bars presents noserious problems. The secret of success and wherein the problems ariseis in handling the metal from the time it is poured from the ladle untilit leaves the mold.

The tundish plays an important role in this process. It provides a meansfor controlling the rate of flow by regulating the metal level in it.Also, here is where provisions must be made for holding back slag sinceif any goes through into the mold it eventually will cause sticking.

The particular problem with which the present invention is concerned, isin the continuous casting of steel where a deoxidizer, particularlyaluminum, is added to the molten batch. As the stream of steelcontaining aluminum flows to the mold, from the tundish nozzle, spinelsare formed. These spinels appear as large icicles which seriouslyinterfere with the stream ofmetal.

Accordingly, it is an object of the present invention to provide a meansfor preventing the formation of spinels in aluminum containing moltensteel in the continuous casting process.

Another object of the invention is to provide an improved tundish nozzleconstruction for use in the process of the invention.

Other objects of the invention will, in part, be apparent hereinafter.

In order to more fully understand the nature and scope of the presentinvention, reference should be had to the following detailed descriptionand drawings, in which:

FIG. 1 is a schematic diagram of a portion of a continuous castingoperation, employing the concepts of the present invention; and

FIG. 2 is a perspective view of a tundish nozzle according to thepresent invention.

Briefly, according to one embodiment of the present invention, steel iscontinuously cast by pouring a prepared molten steel into a transferladle. In the ladle, a deoxidizer (i.e., aluminum) is intermixed withthe steel. The steel is then transferred to a tundish and is finallypassed in a uniform stream from the tundish through a tundish nozzle toa mold. As the metal stream exits from the tundish nozzle, a surroundingcurtain of inert gas is applied thereto between the tundish and the moldto prevent-the formation of spinels in the steel.

The curtain of gas is applied through a circular tubular conduitdisposed about the lower extremity of the tundish nozzle. The conduitcontains a plurality of apertures opening toward the metal stream. Theconduit also contains means connecting it to a source of inert gas.Suitable inert gases for use herein are carbon dioxide, nitrogen, heliumand argon.

The term spinel refers to a group of minerals which crystallize in thecubic systems, and which have the formula RO-R O The RO may consist ofone or more of the bivalent oxides MgO, FeO, MnO, or ZnO. The R 0 mayconsist of one or more of the trivalent oxides; A1 0 Cr O or Fe O Theusual and most troublesome spinel formed when employing an aluminumdeoxidizer is FeO-Al O However, various spinels may form using otherdeoxidizers.

Referring to the drawings, in FIG. 1, a ladle of steel 10 is placedabove a tundish 11 in such a position to continuously discharge a streamof molten metal 12 to the tundish, and at such a rate as to maintain asubstantially even bath depth in the tundish. A nozzle 13, according tothis invention, opens from the bottom of the tundish, and is sopositioned that its bottom orifice discharges a stream 14 ofsubstantially constant volume and cross sectional dimension into themold cavity 15 wherein a shaping and skin formation is caused to formthe steel strip 16.

As is shown more clearly in FIG. 2, the nozzle 13 consists of acylindrical shell 17 of refractory material. The shell has an upperextremity 18 and a lower extremity 19. A tubular i.e., donut shapedconduit 20 is concentrically secured to the lower extremity of theshell. The conduit may be fabricated of any material capable ofwithstanding the temperatures prevalent in the area employed. Theconduit may be secured to the nozzle by any method known to thoseskilled in the art. The tubular conduit contains a plurality ofapertures 21 opening in the direction of the lower extremity 19, of theshell. At least one aperture 22 therein, is adapted for interconnectionof the conduit with an inert gas source. As in FIG. 1, the gas source isindicated generally at 23 and is connected to the conduit by means of apipe 24.

The dimensions for the tundish and nozzle vary, depending upon theinstallation in which they are used. The shape of the nozzle is alsovariable, depending upon the desire of a user. It can be generallyinverted bell shaped with an orifice opening through the small end ofthe bell. It can be a truncated, cone shape with the exit orifice formedthrough the smaller end of the cone.

Referring again to FIG. 1, as the stream 14 passes between the bottomorifice of the tundish nozzle and the mold cavity 15, a curtain of inertgas 25 completely envelopes the stream so as to prevent the formation ofspinels as hereinbefore described.

The strip 16 passes downwardly between rollers 26 until it eventually isentirely solidified, at which point it is cut into lengths, as at 27,whereat we have schematically indicated an oxyacetelene burner 28cutting off lengths of steel 29 in the container 30. The container 30 ispivoted about pin 31. As soon as a length of steel 27 has been cut, thecontainer rotates, as shown in dotted lines to a substantiallyhorizontal position and the cut billet or length of steel 27 isdischarged onto, for example, a conveyor system for movement toadditional treatment stages, storage, etc. (not shown).

Having thus described the invention in detail and with sufiicientparticularity as to enable those skilled in the art to practice it, whatis desired to have protected by Letters Patent is set forth in thefollowing claims.

I claim:

1. A nozzle, suitable for use in tundish ladles consisting essentiallyof a cylindrical shell of refractory material defining a nozzle opening,said shell having an upper extremity and a lower extremity, the lowerextremity having concentrically secured thereabout and in contiguouscontact therewith a tubular conduit having a plurality of aperturestherein opening in planes parallel to the nozzle opening and in thedirection of the lower extremity of the nozzle and at least one aperturetherein adapted for interconnection with an inert gas source.

2. The nozzle of claim 1 in which said conduit is generally donutshaped.

References Cited UNITED STATES PATENTS 2,871,529 2/ 1959 Kirkpatrick164-283 2,791,812 5/1957 Dangelzer et a1 164283 2,692,410 10/ 1954Chadwick et al. 1642-83 X 1,324,458 12/1919 McIntosh 164-66 X 42,376,518 5/ 1945 Spence 164-66 3,125,440 3/1964 Hornak et al. 3,174,2003/ 1965 Keel et al. 3,089,209 5/ 1963 Phillips et al. 3,245,126 4/ 1966Phillips et a1.

FOREIGN PATENTS 913,604 6/ 1946 France.

867,735 2/ 1953 Germany.

844,806 7/ 1952 Germany.

781,276 8/ 1957 Great Britain.

781,277 8/1957 Great Britain.

41 1,245 4/ 1966 Switzerland. 1,395,648 3/1965 France.

I. SPENCER OVERHOLSER, Primary Examiner. V. RISING, Assistant Examiner.

US. Cl. X.R.

